{"operation":"document","citation":"PI-03-0100","title":"Pacific Gas and Electric Company — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2003-02-14","effective_on":null,"summary":"PI-03-0100 response to Pacific Gas and Electric Company concerning 192.479.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-03-0100.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-03-0100.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-03-0100","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/2003/g03-02-14_Bhattacharya_192.479-nlmx.pdf","body":"<<<PAGE 1>>>\n\nPI-03-0100\nU.S. Department of Transportation\nResearch and Special Programs Administration\n400 Seventh Street, S.W.\nWashington, D.C. 20590\nFebruary 14, 2003\nMr. Shan Bhattacharya, P.E.\nVice President, Engineering and Planning\nPacific Gas and Electric Company\n123 Mission Street, Room 1521\nSan Francisco, CA 94105\nDear Mr. Bhattacharya:\nThis is in response to your request of July 29, 2002, for an interpretation of the gas pipeline atmospheric\ncorrosion requirements at 49 CFR § 192.481. You ask whether it is the intent of this section to require operators to\nmonitor for atmospheric corrosion \"in areas that are not subject to atmospheric corrosion.\"\nSection 192.481 states that operators shall evaluate each onshore pipeline that is exposed to the\natmosphere at least every three years and take remedial action whenever necessary to maintain protection against\natmospheric corrosion. This section does not exempt pipelines that are in areas initially determined to have a\nnoncorrosive atmosphere under § 192.479, but rather requires periodic evaluation of all pipelines exposed to the\natmosphere.\nCorrosion can, and does, occur in areas that, in general, have a noncorrosive atmosphere. Local moisture\nconditions, chemicals in the environment, and air-soil interfaces may result in severe corrosion in areas where corrosion\nis not expected. Periodic evaluation is necessary to identify and remediate these conditions for every pipeline facility\nexposed to the atmosphere. This requires an investigation of the conditions that exist in the immediate area of an\nexposed pipeline. A general or regional determination that a corrosive atmosphere does not exist is insufficient to meet\nthis requirement.\nPacific Gas and Electric (PGE) appears to be basing its determination of \"zones or areas of its service territory\nwhere a corrosive atmosphere exists\" solely on regional moisture conditions. If that is the case, it has not considered all\nconditions that can lead to corrosion. Furthermore, § 192.479 does not establish a two-class system for the periodic\ncorrosion inspections—one for pipelines in areas documented to be noncorrosive and one for areas subject to corrosion.\nEven for areas with a generally noncorrosive atmosphere, periodic evaluations are required to ensure that local\nconditions are not causing atmospheric corrosion.\nTherefore, all pipeline facilities exposed to the atmosphere must be periodically monitored for evidence of\natmospheric corrosion. A general determination of broad zones of noncorrosive atmospheric conditions based on a\nsample survey may be useful, but does not fully meet the intent of § 192.481, which requires periodic evaluation of\neach pipeline exposed to the atmosphere. Inspection data gathered during routine service calls, patrols, and five-year\nleak surveys can be used to meet this requirement, provided personnel performing these tasks are qualified to inspect\nfor corrosion.\nIf you have any further questions about the pipeline safety regulations, please contact me at (202) 366-4565.\nSincerely,\nRichard D. Huriaux,\nP.E. Manager, Regulations\nOffice of Pipeline Safety\n\n<<<PAGE 2>>>\n\nPacific Gas and Electric Company\n123 Mission Street, Room 1521\nSan Francisco, CA 94105\nJuly 29, 2002\nMr. Richard D. Huriaux\nOffice of Pipeline Safety\nResearch and Special Programs Administration\nU.S. Department of Transportation,\n400 Seventh Street, S.W., Rm. 7128\nWashington D.C. 20590-0001\nDear Mr. Huriaux:\nSubject: Interpretation of 192.481 Atmospheric corrosion control: Monitoring\nThis letter is to request an interpretation of the intent of 49 CFR Section 192.481. Section 192.481 is summarized as:\n\"After meeting the requirements of Sections 192.479 (a) and (b), each operator shall, at intervals not exceeding three\nyears ... reevaluate each pipeline that is exposed to the atmosphere and take remedial action whenever necessary to\nmaintain protection against atmospheric corrosion.\"\nIs it the intent of Section 192.481 to require operators to monitor all above ground pipelines, including service risers, for\natmospheric corrosion, or only those above ground pipelines in areas subject to atmospheric corrosion as established in\nSections 192.479 (a) and (b)?\nIn other words, is it the intent of the code to require operators to monitor for atmospheric corrosion in areas that are\nnot subject to atmospheric corrosion?\nSections 192.479 (a) and (b) clearly makes a distinction between areas subject to atmospheric corrosion and those that\nare not. Section 192.479 (a) allows operators not to comply with that paragraph if it can demonstrate by test, etc., that,\nfor certain areas, a corrosive atmosphere does not exist. Section 192.481 starts by saying, \"After meeting the\nrequirements of Sections 192.479 (a) and (b)...\" Therefore, the \"reevaluation\" requirement of Section 192.481 would\nlogically refer only to those areas subject to atmospheric corrosion.\nOther sections of the code follow this pattern. For example, Section 192.455(f)(1) states that external corrosion control\nrequirements do not apply to electrically isolated, metal alloy fittings in plastic pipelines, if an operator can show by\ntest, etc., that adequate corrosion control is provided by the alloy composition and the fitting is designed to resist localized\ncorrosion pitting. The external corrosion control monitoring requirements of Section 192,465 do not require the\noperator to reevaluate the adequacy of corrosion control measures on those fittings that the operator determined in\nSection 192.455 were not subject to external corrosion.\nPacific Gas and Electric Company has determined and established zones or areas of its service territory where a corrosive\natmosphere exists. The Company currently monitors all aboveground pipelines located in those areas for indications\nof atmospheric corrosion, and takes appropriate remedial actions as necessary as required by Section 192.481. It does not\nseem logical that the code would require operators to monitor for atmospheric corrosion in areas that are not subject to\natmospheric corrosion.\nIf it is the intent of Section 192.481 to require operators to \"reevaluate\" each pipeline exposed to the atmosphere,\nincluding service risers, regardless of whether or not the pipeline is exposed to a corrosive atmosphere, then what does\n\"reevaluate\" mean? For example, if the Company were to verify its corrosive atmosphere zones every three years and\ntake remedial action when necessary, would this practice be in compliance with Section 192.481? Pacific Gas and\nElectric Company would perform this reevaluation by test and investigation through the use of sample sites. The sample\nsites would be periodically evaluated and the boundaries of the corrosive atmosphere areas would be adjusted\naccordingly. Additionally, inspection data gathered during routine service calls, patrols, and 5-year leak surveys would be\nused to evaluate the corrosive area boundaries.\nThank you for your attention to this matter. Please contact Tom Robinson at (415) 9738180 if you have any questions or\nneed additional information.\nSincerely,\nShan Bhattacharya","truncated":false,"body_characters":7115}